فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri - Paris Observatory

A fixed space in which physical phenomena occur and
whose properties do not depend on what occupies it, nor on the observer.
It is a distinguished frame of reference that could show bodies to be truly moving
or truly at rest. Absolute space is one of the basic assumptions of
→ Newtonian mechanics,
but it was abandoned in Einstein's → special relativity.
See also → absolute time; → space-time.

A bounded space the surface of which has the property that if one travels in any direction
upon it without changing direction, one will end up back to the departure point. An
example is a sphere. Triangles which lie on the surface of
a closed space will have a sum of angles which is greater than 180°.
An closed space has a positive → curvature.
See also → closed Universe,
→ open space.

NASA's mission to explore the two largest objects in the
→ asteroid belt, the asteroid Vesta and the
→ dawarf planet
Ceres, gathering data relating to their composition, internal structure, density and
shape. Launched in September 2007, Dawn
entered the orbit of → Vesta
in July 2011 and spent 16 months there
before leaving for → Ceres.
It entered Ceres orbit on March 6, 2015.
The Dawn spacecraft is made of aluminium and graphite composite, it
has a dry mass of 747.1 kg and a mass of 1217.7 kg when fully fuelled
prior to launch. The spacecraft is a box-shaped design measuring 1.64m
× 1.27m × 1.77m.

A space in which the → distance between any two points is given by
the → Pythagorean theorem:
d2 = (Δx)2 + (Δy)2 +
(Δz)2, where d is distance and Δx,
Δy, and Δz are differential
→ Cartesian coordinates.
Euclidean n-space Rn is the set of all
column vectors with n real entries.

An intergovernmental organisation dedicated to space research and
technology as well as peaceful exploration of space, founded in
1975. It is headquartered in Paris and currently comprises 18 member
states and one associated state (Canada). ESA has developed the Ariane
series of space launch vehicles, and supports a launch facility in
French Guiana. Moreover, ESA has four major research centers: The
European Space Research and Technology Center (ESTEC), located in
Noordwijk, the Netherlands, is the primary research center and manages
the satellite projects. The European Space Operations Center (ESOC),
situated in Darmstadt, Germany, is responsible for satellite control,
monitoring, and data retrieval. The European Space Research Institute
(ESRIN), located in Frascati, Italy, supports the ESA documentation
service and manages the data obtained from remote sensing
satellites. The European Astronaut Center (EAC), located in Cologne,
Germany, is responsible for the selection and training of astronauts
for space station missions. The European Space Astronomy Centre
(ESAC), located in Villafranca del Castillo, Madrid, Spain, which
holds scientific operations centres as well as archives. Some of the past ESA
missions are the following ones. The Giotto space probe,
which enabled examination of the core of → Halley's Comet
in 1986. ESA also developed the Ulysses spacecraft (launched 1990) to explore the
Sun's polar regions. Similarly, ESA established a system of
meteorological satellites known as Meteosat. In 2003 ESA launched the
Mars Express orbiter and its lander, Beagle 2. In 2009 ESA launched
→ Planck Satellite, that is designed to study the
→ cosmic microwave background,
and the → Herschel Satellite, an infrared observatory
that is the largest telescope in space.

A space project, initially → LISA,
consisting of a configuration of three satellites, aimed to
detect low frequency → gravitational waves that cannot
be measured by ground-based detectors. The detection range will be
from about 0.1 milliHz to 1 Hz.
One "mother" and two "daughter" spacecrafts will be brought into an
orbit around the Sun, which is similar to the Earth's orbit. The
satellites will fly in a near-equilateral triangle formation, with a
constant distance of one million km between, following the
Earth along its orbit at a distance of around 50 million km.
The mother spacecrafts carries two and each of the daughter spacecraft
carry one free-flying → test masses
that will be kept as far as possible free of external
disturbances. The mutual distances of the test masses from satellite
to satellite will be measured by means of high-precision,
→ Michelson-like laser → interferometry.
In this way, the extremely small distance variations between the test
masses of two satellites can be detected which are caused by the
passages of a gravitational waves. The required measurement accuracy
of the distances amounts to typically 1/100 of the diameter of a
hydrogen atom (10-12 m) at a distance of two million
km.

A space observatory, formerly named GLAST, devoted to the study of
→ gamma rays
emitted from astrophysical objects.
Developed by NASA in collaboration with the U.S. Department of Energy,
along with important contributions from academic institutions and
partners in France, Germany, Italy, Japan, Sweden, and the United
States, Fermi was launched on June 11, 2008.
The main instrument, the Large Area Telescope (LAT), is an imaging
→ camera covering the
energy range from about 20 → MeV to more than 300
→ GeV. Such gamma rays
are emitted only in the most extreme conditions, by particles moving
very nearly at the → speed of light.
The LAT's → field of view covers
about 20% of the sky at any time, and it scans continuously, covering
the whole sky every three hours.
Another instrument, the Gamma-ray Burst Monitor (GBM) has a field of view several times
larger than the LAT and provides → spectral coverage
of → gamma-ray burst
that extends from the lower limit of the LAT down to 10 → keV.

A space mission whose main goal was to explore → Jupiter
and its moons and rings.
The spacecraft was launched on October 19, 1989, arrived at Jupiter in December 1995.
It disappeared on September 21, 2003, after eight years orbiting Jupiter,
when mission controllers crashed it into → Jupiter's atmosphere.
On December 7, 1995, Galileo's probe dived into Jupiter's atmosphere, and
measured atmospheric pressure, density, and composition,
and explored the planet's → radiation belts.
Galileo had two parts: an orbiter and a descent probe that parachuted into
Jupiter's atmosphere. The orbiter sent back hundreds of pictures of the four large
→ Galilean satellites of Jupiter
(→ Io, → Europa,
→ Ganymede, and → Callisto).
It made many discoveries during its eight years looping
around Jupiter. It found evidence for layers of salt water below the
surface on Europa, Ganymede, and Callisto, and measured high levels of
volcanic activity on Io. When → Shoemaker-Levy
slammed into Jupiter in 1994, Galileo had the only direct view of the
→ comet striking Jupiter's
atmosphere. Galileo determined that → Jupiter's rings
are formed from
dust hurled up by → meteorite impacts on planet's inner
moons. Measurements by the orbiter's → magnetometer
revealed that Io, Europa, and Ganymede have metallic cores, while Callisto does
not. Also, Galileo discovered that Ganymede possesses its own
→ magnetic field;
it is the first moon known to do so. The orbiter also found that
the Galilean satellites all have thin atmospheres.
During it's trip from Earth to Jupiter, Galileo passed by and studied
two asteroids: → Gaspra in 1991 and
→ Ida in 1993, around which it discovered
→ Dactyl,
the first moon orbiting an asteroid (windows2universe.org).

A generalization of Euclidean space in a way that extends methods of
vector algebra from the two- and three-dimensional spaces to
infinite-dimensional spaces.
Multi-dimensional space in which the eigenfunctions of quantum mechanics are
represented by orthogonal unit vectors.

Named after the German mathematician David Hilbert (1862-1943),
recognized as one of the most influential mathematicians of the 19th and early
20th centuries for his numerous contributions to various areas of mathematics;
→ space.

Hubble Space Telescope (HST)

دوربین ِ فضایی ِ هابل، تلسکوپ ِ ~ ~

durbin-e fazâyi-ye Hubble, teleskop-e ~ ~ (#)

Fr.: télescope spatial de Hubble

A telescope of 2.4 m in diameter, a joint NASA and ESA project,
launched in 1990 into a low-Earth orbit 600 km above the ground. It was
equipped with a collection of several science instruments that worked
across the entire optical spectrum (from infrared, through the
visible, to ultraviolet light). During its lifetime Hubble has become
one of the most important science projects ever.

A European Space Agency satellite which carried the most sensitive infrared telescope
ever launched. It operated between November 1995 and April 1998 and
made particularly important observations of the dusty regions of the Universe.
ISO was equipped with four science instruments: an infrared camera (CAM), a
long-wavelength spectrometer (LWS), a photo-polarimeter (PHT), and a
short-wavelength spectrometer (SWS). The instruments jointly covered wavelengths
from 2.5 to around 240 microns with spatial resolutions
ranging from 1.5 arcseconds to 90 arcseconds. Its 60 cm diameter telescope was cooled by
superfluid liquid helium to temperatures of 2-4 K. The mission was a great technical,
operational and scientific success. During its routine operational phase, ISO
successfully made some 30,000 individual imaging, photometric,
spectroscopic, and polarimetric observations ranging from objects in
our own solar system to the most distant extragalactic sources.

A large, infrared space telescope with a mirror 6.55 m in diameter,
scheduled for launch in 2018. JWST's instruments will work
primarily in the infrared range of the electromagnetic spectrum, with some capability in the
visible range (0.6 to 28 μm). The scheduled instruments are
Near IR Camera (NIRCam, field of 2.2 x 4.4 arcmin, wavelength range 0.6-5 μm),
Near IR Spectrograph (NIRSpec, 3.5 x 3.5 arcmin, 0.6-5 μm, resolving powers of
~ 100, ~1000, and ~3000),
Mid IR Instrument (MIRI, 1.4 x 1.9 arcmin, 5-27 μm, R ~ 3000), and
Fine Guidance Sensor (FGS, 2.3 x 2.3 arcmin, 0.6-5 μm, R ~ 100).
The successor to the → Hubble Space Telescope
will be placed in an orbit about 1.5 million km from the Earth, at the
→ Lagrangian point L2.
The JWST project is a → NASA-led international collaboration with
the → European Space Agency and the
Canadian Space Agency. The scientific goals of JWST can be grouped under four broad topics:
first light after the Big Bang; galaxy formation; birth of stars and protoplanetary systems;
and planetary systems and the origins of life.

Named in honor of James E. Webb (1906-1992), who
headed NASA from 1961 to 1968, overseeing all the
manned launches in the Mercury through Gemini programs, until
before the first manned Apollo flight; → space;
→ telescope.

Kepler spacecraft

تلسکوپ ِ فضایی ِ کپلر

teleskop-e fazâyi-ye Kepler

Fr.: télescope spatial de Kepler

A → NASA space telescope launched in March 2009 to discover
Earth-size planets using the → transit method.
The telescope has a diameter of 0.95 m and its
only instrument is a → photometer
that continuously monitors the brightness of over 145,000
→ main sequence stars in a fixed field of view of
115 deg2 (about 12° diameter). The expected
mission lifetime is 3.5 years extendible to at least 6 years.

A collaborative project between → NASA
and → ESA
to develop and operate a space-based gravitational wave
detector sensitive at frequencies between 0.03 mHz and 0.1 Hz. LISA
detects gravitational-wave induced strains in → space-time
by measuring
changes of the separation between fiducial masses in three spacecraft
5 million km apart. Ultimately, NASA and ESA decided in 2011 not to proceed
with the mission. LISA was not the highest ranked mission in the 2010
Decadal Survey and funding constraints prevented NASA from proceeding
with multiple large missions (http://lisa.nasa.gov).
→ LISA pathfinder.

An set of points such that the distance between every pair of points is defined
by a → distance function with
the following properties: 1) the distance from
the first point to the second equals zero if and only if the points
are the same, 2) the distance from the first point to the second
equals the distance from the second to the first, and 3) the sum of
the distance from the first point to the second and the distance from
the second point to a third exceeds or equals the distance from the
first to the third.
In mathematical language, the properties, for a nonempty set X, can be
expressed as:
1) d(x,y)≥ 0 and d(x,y) = 0 if and only if x = y.
2) d(x, y) = d(y,x) for all x, y ∈ X.
3) d(x,z)≤ d(x,y) + d(y,z) for all x, y,
and z ∈ X. Also called → triangle inequality.